Conrad Murray trial: Jackson 'addicted to Demerol'

Singer Michael Jackson was probably addicted to the painkiller Demerol, a witness for the defence in the trial of his doctor, Conrad Murray, has said.

Dr Robert Waldman testified that records from Jackson's dermatologist show the singer was receiving large doses of the drug in the months ahead of his death.

He said one of the symptoms of Demerol withdrawal included insomnia.

Dr Murray has pleaded not guilty to involuntary manslaughter.

His lawyers claim Jackson gave himself the fatal dose while Dr Murray was out of the room.

The defence also called their own propofol expert, Dr Paul White.

Dr White told the court on Thursday he said he would not have expected the pop superstar to be killed from the drugs which Dr Murray said he had given to the singer.

He is the last witness for the defence and is expected to continue testifying on Friday, including giving an alternate theory about how Jackson died.

However, because of a late admission by the defence that Dr White would be using a new computer simulation to illustrate his theory, Judge Michael Pastor has given prosecutors the weekend to analyse the data before cross-examining the defence's expert.

Prosecutors told the judge they were surprised by the new development and needed time to study the software program.

Lawyers for Dr Conrad Murray have moved quickly through witnesses since beginning their case earlier this week, including former patients of the doctor.

Medical records

Dr Waldman was testifying largely in the place of Dr Arnold Klein, Jackson's dermatologist. Using Dr Klein as a witness was ruled out in the trial because his care of Jackson was not being investigated.

Using the dermatologist's records, he testified that over three days in April 2009, Jackson received 775mg of Demerol, during the same period that Dr Murray was giving Jackson propofol.

Dr Waldman told jurors that was a "large dose" for a dermatology procedure in an office.

On cross-examination, however, prosecutor David Walgren asked Dr Waldman about legal obligations for doctors, including a requirement to keep accurate and detailed records.

Dr Murray told police he had kept no records on his treatment of Jackson.

Dr Paul White said after reading documents regarding the case he was "perplexed".

"I would not have expected Michael Jackson to have died," if the dose Dr Murray said he had given Jackson was correct.

But if Jackson's doctor did in fact put him on an IV drip of propofol and leave him unattended, Dr White said he could not justify it, AP reports.